四川盆地川西坳陷东坡沙溪庙组油气成藏关键时刻研究

四川盆地川西坳陷是印支期以来龙门山挤压推覆所形成的前陆盆地，中段东坡地区包含合兴场—高庙子、丰谷、永太、中江—回龙和知新场—石泉场共计5个三维地震勘探区块，涉及3个构造区带。通过研究烃源岩生烃演化史并对研究区6口井22块流体包裹体样品进行荧光观察、显微测温、测盐等系统分析，结果表明:上三叠统须家河组五段烃源岩于151~145 Ma进入生烃门限，130 Ma达到生烃高峰；研究区侏罗系沙溪庙组砂岩储层发生过3期与油气成藏有关的流体活动，分别发生在距今141~128 Ma（J₃-K₁），105~88 Ma（K₁-K₂），83~68 Ma（K₂），成藏关键时刻主要在烃源岩的生烃高峰期130~68 Ma（K₁-K₂）。 

Key moments for hydrocarbon accumulation in Shaximiao Formation on the eastern slope of West Sichuan Depression,Sichuan Basin

The West Sichuan Depression in the Sichuan Basin is a foreland basin formed under the compressional thrusting of the Longmen Mountain. 3D seismic was obtained on five exploration blocks on the eastern slope of the central depression, including Hexingchang-Gaomiaozi, Fenggu, Yongtai, Zhongjiang-Huilong and Zhixinchang-Shiquanchang, covering three tectonic belts. The hydrocarbon evolution history of source rocks was studied, and 22 fluid inclusion samples from 6 wells were analyzed using fluorescence, homogenization temperature and salinity measurements. Source rocks in the fifth member of the Upper Triassic Xujiahe Formation entered the hydrocarbon generation threshold at 151-145 Ma, and reached a peak at 130 Ma. Three stages of fluid activities related to hydrocarbon accumulation took place in sandstone reservoirs in the Jurassic Shaximiao Formation at 141-128 Ma (J₃-K₁), 105-88 Ma (K₁-K₂) and 83-68 Ma (K₂), respectively. The peak of hydrocarbon generation of source rocks at 130-68 Ma (K₁-K₂) is the key moment for hydrocarbon accumulation.